The oil level in an engine crankcase or transmission, specifically on vehicles such as automobiles and boats, is traditionally manually checked by means of a dipstick which extends through a tube into the oil reservoir, with the dipstick being manually removed to permit visual inspection of the oil level indicator scale thereon. The manually removable dipstick, while having been extensively utilized for many years, is nevertheless undesirable inasmuch as it requires direct access to the engine, which access is often rather difficult, and hence, there is a tendency to omit periodic checking of the oil level. This in turn can hence result in serious engine damage due to the engine being operated with inadequate quantities of oil for lubricating same. Over the years, there have been proposed various techniques for permitting remote reading or sensing of the oil level, specifically in the crankcase of a vehicle engine. These proposals, however, have generally involved rather complex systems which employ a mechanical linkage extending from the engine crankcase to a remote location, such as a vehicle dashboard, or in the alternative employ some type of pumping mechanism for sensing oil level in the crankcase. These known devices have hence generally required complex linkage or transmission arrangements, or in the alternative have required modification of the engine so as to accommodate the level-sensing system. These systems have hence been less than desirable. Typical systems of this type are illustrated by U.S. Pat. Nos. 1,508,969, 1,521,195, 1,526,377, 1,781,756 and 2,624,790.
There has also been proposed a system for determining the quantity of liquid in a tank by utilizing a manually actuated pressure system for determining the height of the liquid column within the tank. In this system, the upper portion of the tank is drilled to provide an access hole, and an elongated piece of tubing is inserted downwardly through the hole so that the open lower end of the tubing is positioned closely adjacent, such as about one inch from, the bottom of the tank. The other end of the tubing is connected to an instrument panel which has a pressure gauge and a pressure actuator associated therewith. By manually actuating the pressure actuator so as to pressurize the column of air in the tubing, this hence enables a determination as to the height of the liquid in the tank (that is, the height of the liquid above the open lower end of the tubing) since, by gradually pumping the actuator to build up pressure, the gauge will indicate this pressure buildup, which pressure buildup occurs until the air pressure equals the column-height pressure of the liquid in the tank, after which air will bubble or bleed out of the open lower end of the tube and hence stabilize the pressure in the system. This known system is hence designed for determining the height of liquid in the tank, and is not designed for sensing the "low" or "add" level such as in a conventional engine housing. Further, in this known system, the requirement of drilling a hole in the housing and then inserting a tube therethrough makes installation of the system undesirably complex. This known system has, however, been utilized on boats and the like for determining the quantity of liquid in tanks, such as for determining the quantity of fuel in the fuel tank.
Accordingly, the present invention relates to an oil level indicator system and, more particularly, to a system which remotely indicates when oil should be added to the reservoir due to the level in the reservoir being below the lowest acceptable limit. This improved system is highly desirable since it can be readily utilized in conjunction with existing engines or transmissions by utilizing the standard dipstick tube associated therewith, whereby the engine or transmission does not require any rebuilding or modifying, and at the same time the improved system does not require any complex mechanical linkages. This improved system hence effectively overcomes the disadvantages associated with prior remote oil-level indicator systems.
In the improved system of the present invention, a level-sensing tube is fixedly positioned within and inserted through the standard dipstick tube as fixedly associated on most engines and transmissions. This level-sensing tube is inserted through the dipstick tube and positioned such that the lower end of the level-sensing tube is disposed substantially at the "low" or "add" oil level. The level-sensing tube in turn is connected through a main conduit, such as an elongated flexible tube, to a pressure pulse actuator which is remotely located, such as mounted on the dashboard of an automobile or boat. This pressure pulse actuator, which in the preferred embodiment is a manually actuated air cylinder, is capable of transmitting a pressure pulse through the conduit and through the level-sensing tube into the oil reservoir. A secondary conduit is connected between the main conduit and an indicator, such as a pressure gauge, which is also mounted on the vehicle dashboard. If the oil level in the reservoir is above the "low" or "add" level, then the lower end of the level-sensing tube is immersed in the oil so that, when a mass of air is transmitted through the level-sensing tube, the oil which closes off the lower end of the tube causes a pressure buildup which is transmitted through the secondary conduit so as to cause movement of the indicator associated with the pressure gauge into a "safe" range, which indicator remains in this "safe" " range to indicate that the oil level is satisfactory. On the other hand, if the level of oil in the reservoir is at or below the "add" level, then the lower end of the sensing tube is exposed and hence in communication with the region of the reservoir located above the oil, which region is filled with gas, namely air. Hence, when the pressure pulse actuator is activated, the mass of air flows through the main conduit and the level-sensing tube into the upper region of the reservoir, whereupon there is rapid dissipation of the air mass, and hence no significant buildup of pressure. While the pressure pulse may cause an initial displacement of the pressure gauge indicator due to flow resistance within the conduits, nevertheless this is only a momentary displacement and the indicator rapidly returns to its initial position so as to indicate that the oil level is low, and that further oil should be added.
The improved system of this invention is highly desirable due to its structural simplicity, its ease of use, its long-term dependability in term of reliable and maintenance-free operation, its ease of adaptability on all types of existing engines, specifically all types of vehicle engines, and its simplicity of operation.
Other objects and advantages of the present invention will be apparent after reading the following specification and inspecting the accompanying drawings.